Titanium part having an anodized layer

Abstract

An enclosure for a portable electronic device can include a titanium substrate defining a textured surface and a nominal surface. The titanium substrate can include a first region that extends above the nominal surface and a second region adjacent to the first region and extending below the nominal surface. A separation distance between an apex of the first region and a bottom of a trough defined by the second region can be at least 1 micrometer. A metal oxide layer can overlay the trough defined by the second region.

What is claimed is: 
     
       1. An enclosure for a portable electronic device, the enclosure comprising:
 a titanium substrate defining a textured surface and a nominal surface, the titanium substrate comprising:
 a first region that extends above the nominal surface; 
 a second region adjacent to the first region and extending below the nominal surface, a separation distance between an apex of the first region and a bottom of a trough defined by the second region being at least 1 micrometer; and 
 a metal oxide layer overlaying the trough defined by the second region; 
 
 wherein the titanium substrate further comprises a first grain structure and a second grain structure, the second region corresponding to a grain boundary that separates the first grain structure from the second grain structure. 
 
     
     
       2. The enclosure of  claim 1 , wherein the enclosure has a color having an a* value between −10 to 15 and a b* value between −35 to 30 in a CIE L*a*b* color space. 
     
     
       3. The enclosure of  claim 2 , wherein the color is dependent upon a thickness of the metal oxide layer. 
     
     
       4. The enclosure of  claim 3 , wherein the metal oxide layer has a thickness between 20 nanometers and 200 nanometers. 
     
     
       5. The enclosure of  claim 1 , wherein the metal oxide layer comprises an anodized layer formed from the titanium substrate. 
     
     
       6. The enclosure of  claim 1 , wherein the metal oxide layer comprises a first metal oxide layer having a first thickness that overlays the apex of the first region and a second metal oxide layer overlaying the trough defined by the second region, the second metal oxide layer having a second thickness different than the first thickness. 
     
     
       7. The enclosure of  claim 1 , wherein the first grain structure is oriented in a first orientation and the second grain structure is oriented in a second orientation different from the first orientation.